Merge branch 'net-bridge-convert-multicast-to-generic-rhashtable'

Nikolay Aleksandrov says:

====================
net: bridge: convert multicast to generic rhashtable

The current bridge multicast code uses a custom rhashtable
implementation which predates the generic rhashtable API. Patch 01
converts it to use the generic kernel rhashtable which simplifies the
code a lot and removes duplicated functionality. The convert also makes
hash_elasticity obsolete as the generic rhashtable already has such
checks and has a fixed elasticity of RHT_ELASTICITY (16 currently) so we
emit a warning whenever elasticity is set and return RHT_ELASTICITY when
read (patch 03). Patch 02 converts the multicast code to use non-bh RCU
flavor as it was mixing bh and non-bh. Since now we have the generic
rhashtable which autoshrinks we can be more liberal with the default
hash maximum so patch 04 increases it to 4096 and moves it to a define in
br_private.h.

v3: add non-rcu br_mdb_get variant and use it where we have
    multicast_lock, drop special hash_max handling and just set it where
    needed and use non-bh RCU consistently (patch 02, new)
v2: send the latest version of the set which handles when IGMP snooping
    is not defined, changes are in patch 01
====================

Signed-off-by: David S. Miller <davem@davemloft.net>